1. Technical Field
The present invention relates to an intake system preferably applied to, for example, a multiple cylinder engine for a motorcycle.
2. Background Art
For example, a multiple cylinder engine mounted on a motorcycle includes an intake system of a multi-throttle type having one throttle body for each cylinder. As the intake system of this type, a manual intake system, in which a throttle grip and throttle valves are coupled mechanically by a throttle cable and all the throttle valves are opened and closed mechanically by a throttle grip rotating operation of a rider, is generally used.
On the other hand, recently, there has also been proposed an electric intake system in which an electric motor is coupled to throttle valves via a link mechanism or the like. A throttle grip rotating operation of a rider is detected and all the throttle valves are opened and closed by the electric motor according to this detected rotating operation.
Incidentally, in both the manual type and the electric type, the conventional intake system is constituted so as to control all the throttle valves to open and close uniformly in response to a throttle grip rotating operation of a rider. Therefore, for example, when the rider closes the throttle grip suddenly, all the throttle valves also close suddenly, whereby strong engine brake acts.
However, there is a demand that, depending upon a running state, for example at the time of approaching a corner or at the time of rising from the corner, for example, it is desired to make the engine brake slightly weak even in the case in which the throttle grip is closed suddenly or it is desired to make the rising of a torque slightly gentle even in the case the throttle grip is opened suddenly. In the conventional system, such a demand is coped with by a throttle grip rotating operation of a rider. However, this results in a problem requiring of an excessively high level driving operation from the rider.
The present invention has been devised in view of the conventional situation, and it is an advantage of the present invention to provide an intake system for an engine that can obtain an output characteristic corresponding to a running state without requiring a very high level driving operation from the rider.